The whistleblower who first raised the alarm about what he believed to be attempts to manipulate gas prices has been summoned to Brussels to explain to European Union regulators how the market might have been distorted .

Seth Freedman will meet Maria-Teresa Fabregas-Fernandez, deputy head of securities markets at the European commission, . The unit is considering new regulations for benchmarks and indices, such as the gas price that Freedman claims may have been distorted by traders.

European Union authorities said they could launch a broader international inquiry into the allegations if there was any evidence of financial or energy firms colluding in breach of competition rules. UK gas prices set the benchmark for gas trading across Europe.

The commission's competition authorities are already investigating EU and British banks on suspicion of cartel-like conduct following the scandal earlier this year of the Libor rate-fixing rackets. Last night the European commission said it would await for the results of the UK inquiries of the gas-pricing claims before deciding on its next move.

"The commission is closely following the reports of alleged market manipulation in the UK gas market. At this stage, Ofgem and the FSA [Financial Services Authority] are well-placed to investigate the allegations," said the office of Joaquín Almunia, competition commissioner. "The commission might take action if it becomes aware of a violation of EU competition rules."

A spokesman for Michel Barnier, single market commissioner, said: "If the manipulation described in the press relates to financial markets, it would be illegal under the current market abuse rules that apply in those markets." Barnier's officials have also drafted new rules criminalising serious market abuse and protecting whistleblowers. They hope to have the legislation passed by the spring.

New rules giving national energy regulators in the EU stronger powers to demand information and conduct on-site inspections of energy companies was passed last December and is to be fully operable by next summer.

The regulation, dubbed Remit (regulation on energy markets integrity and transparency), included establishing an EU agency in Slovenia to collate information from national energy regulators and raise the alarm over suspicious trading activities or perceived energy production variations aimed at affecting prices.

"This shows this issue is of concern to us," said Marlene Holzner, spokeswoman for the energy commissioner, Günther Oettinger. "We have dealt with the whole issue of market abuse. We did the new legislation to tackle that."

The British government said it supported the new energy watchdog rules and would be at the forefront of those getting the new regime in place.

"We acted swiftly to tackle the attempted manipulation of Libor and Euribor and we are in the process of giving Ofgem more powers to tackle abuses, including the EU Remit legislation," said a UK spokesman. "These powers will be in place ahead of schedule by the spring, making the UK one of the first countries to do this."

The Labour MEP Arlene McCarthy, who is vice-chairwoman of the European parliament's monetary affairs committee, has also called for a Europe-wide inquiry of conduct in the energy markets. "For some time I have feared there's an extensive cartel culture of market-rigging and price-fixing in the commodities markets.

"Companies guilty of abuse must face the full force of penalties and sanctions and jail for criminal behaviour," she said.

"Following the revelations on the Libor crisis, this is another case of apparent market abuse and manipulation in gas prices, which demonstrates [that] the culture of chasing short-term profits and gains in financial and commodity markets has not changed."

Commission action was necessary at the Europe-wide level, she added, because UK gas set the benchmark for gas trading across Europe.